Assessment of Brain-injury using Radio-Frequency Induction and Microwave Spectroscopy (ABRIMS)

Abstract

Brain-injury is one of the most severe and significant causes of morbidity and death in modern healthcare. Its consequences can exact a heavy toll; leaving survivors with the life-long scars of debilitating personality change, mental illness, epilepsy, speech and language problems, cognitive and executive dysfunction, and mobility and physical impairment and paralysis.

The statistics are stark: Around 350,000 people with brain-injury were admitted to UK hospitals in 2014 with conditions ranging from haemorrhage to stroke. Conservatively, at least 2000 adults a year suffer serious impairments from their injury, and it is the primary cause of disability and death in young people and children. Most concerning of all, these numbers are rising. According to the charity 'Headway', brain-injuries have increased by 10% since 2006.

The chances of recovering after a brain injury are vastly improved if the right therapy can be delivered at the right time, by a clinician equipped with the very-best information on the patient's neurological state.

This proposal takes advantage of recent work on radio-frequency induction (RFI) and microwave (MW) spectroscopy systems for diagnosis of neurological injury. Our innovation is to combine RF and MW measurement of the spectrum in a single system, on the premise that the sum of the parts is greater than the whole. We can exploit the differing contrast ratios in the electrical properties of intracranial tissues over the two regions, combining the data in new ways to radically improve selectivity - that is, the ability to select one effect (a brain-injury) over other confounding physiological and environmental factors that may also affect the measurement.

We are particularly interested in frequencies over the dispersion regions of intracranial tissues - specifically the beta and gamma dispersions. These are regions on the spectrum where the electrical properties change more suddenly as the mechanism for charge flow, or transmission of electric fields, changes from one form to another. These two information-rich regions of the spectra are notable for the markedly different contrast ratios between the different cranial tissues. These different contrast ratios may be used to elucidate properties about the state, condition and progress of certain types of brain injuries, such stroke, haemorrhage and haematoma (bleeding and blood clots), cerebral oedema (swellling), chiefly characterised by volumetric changes of fluids and tissue set within the cranium.

Our aspiration is that this technology, in a compact and portable form, will serve to improve patient outcomes resulting from brain-injury. We envisage a system that could; (1) be deployed at the very earliest stages of patient care, providing time critical diagnosis to speed up treatment delivery; and (2) an intrinsically safe, continuous monitoring tool for dynamic assessment of a brain injury's progression, supplemental to existing neuro-imaging, and give an early warning of rapid and potentially catastrophic patient deterioration while there is still time for surgical intervention.

Planned Impact

Brain-injury and its consequences are a major healthcare challenge in the UK and internationally. This proposal aspires to improve outcomes associated with brain-injury (morbidity, cognitive deficits, death), by using microwave and radio-frequency induction spectroscopy to create a new diagnostic and monitoring tool. This tool has two possibilities for impact:

(1) Provide diagnosis of time-critical neurological injuries at the very earliest stages thus improving outcomes by ensuring treatment is administered without delay. For instance, by identifying type of stroke (ischaemic from haemorrhagic) and detecting strokes with blockage of a large vessel at the earliest possible stage. This could speed up delivery of thrombolytic therapy - a treatment for ischaemic stroke, but harmful if the stroke is haemorrhagic - and reduce delays by diverting appropriate patients with large vessel occlusion directly to centres able to perform mechanical thrombectomy.

(2) Provide a continuous, real-time, bedside monitoring capability post-CT to allow clinicians to track the progress of an evolving brain-injury, and early warning of rapid and catastrophic patient deterioration while preventative action is not a possibility. For example, the system may be used to monitor changes in cerebral oedema (brain swelling) or intracranial pressure in response to drug therapy, or emergent haemorrhage as a serious complication of thrombolytic therapy. It could be used to give an early warning of a catastrophic rise in intracranial pressure, compressing vital brain structures leading to disablement or death of the patient.

Given that the aim is to produce a portable and low-cost system (relative to CT and MRI), we also identify a benefit to developing countries, where instances of brain-injury are rising sharply with increased motor-vehicle use, and where medical and specialist neurosurgical resources are less available. By the same argument, there are also applications wherever access to facility-scale and specialist medical services is limited or sparse, such as extreme or remote locations, conflict zones or battlefield triage.